Discovery 1 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoid)





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    Question 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solenoid)

    Hi all

    I am busy troubleshooting a solenoid issue and found something weird.

    I've gone through these freds:
    https://www.4x4community.co.za/forum...iring-when-hot
    https://www.4x4community.co.za/forum...er-heat-shield
    https://www.4x4community.co.za/forum...rter-acting-up

    From these it sounds (in my understanding anyway) like the solenoid acts only as a relay (meaning it doesn't actuate the bendix or does anything else than connecting heavy current and feeding it to the starter that does the rest)

    My solenoid is weird in terms of when the Disco gets cleaned from below with a pressure washer for a couple of days afterwards it sometimes doesn't do anything other than clicking softly.
    (It does start when cold though. so the symptoms are sometimes also similar to the 'no heatshield between the header pipes and the solenoid' issue, but after a couple of days this also goes away)

    Point is in troubleshooting this (and for my own sanity knowing what to do if this happens out in the stix before I get it sorted properly) I tried to see how easy it would be to get my overweight body in there to either bridge the connections to the solenoid or feed power to the business end contact directly from the battery with a jumper cable.

    What I found confuses me a bit (granted, it doesn't take much to get me confused, but I digress):

    With the ignition in 'on' (dash lights on, immobilizer off and car ready to start) when I bridge the terminals on the solenoid the starter spins up but don't engage to turn the engine.
    Same happens when I attach the jumper cable to the 'business end' of the solenoid (the output terminal at the bottom going into the starter) and touches the other side of the jumper cable to red on the battery.

    If I then turn the ignition key to 'start' the starter spins up and engages immediately. turning the engine and causing that sweet sweet sound of the V8 bursting to life.

    So this is my confusion summed up:
    I thought that there was only power going to the starter through the solenoid and that the bendix then actuates from the same power.
    In testing it looks like there are two feeds somehow needed - one to spin up the starter and another to 'connect' it to the flywheel.

    What am I missing/not understanding ?

    Thanks !
    Last edited by Eisbein; 2019/10/11 at 11:45 AM. Reason: Spelling errors

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi



    Short explanation ! The Thick wire running to the starter is permanently live!
    The thin wire on the Solenoid brings the power from the Ignition switch. The moment you turn the Key the solenoid does 2 things ! It pulls the Plunger that is inside it back and through the action of the fork connected to it the Bendix pushes out and connects the teeth on the flywheel , secondly (here is where the relay theory comes in) the solenoid connects the path of the thick wire , like an relay, to turn the starter motor. So in simple terms the rear black part of the solenoid is the "relay" and the front metal part is the plunger area that activates the Bendix drive!
    Hope this clears it up.

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    Check earth cable to engine, remove,clean and refit.

    Measure voltage on solenoid wire and on starter wire.
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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    Quote Originally Posted by JWR View Post

    Short explanation ! The Thick wire running to the starter is permanently live!
    The thin wire on the Solenoid brings the power from the Ignition switch. The moment you turn the Key the solenoid does 2 things ! It pulls the Plunger that is inside it back and through the action of the fork connected to it the Bendix pushes out and connects the teeth on the flywheel , secondly (here is where the relay theory comes in) the solenoid connects the path of the thick wire , like an relay, to turn the starter motor. So in simple terms the rear black part of the solenoid is the "relay" and the front metal part is the plunger area that activates the Bendix drive!
    Hope this clears it up.
    Aaaaaaaaah

    Thank you for the diagram and explanation.

    Ok - so this makes sense to me then
    I was really under the impression that the solenoid only did the 'small to large current' switching and that the 'bendix movement' was done internal to the starter (btw - on my motorcycle it works that way)

    Is that then the 'click' I hear when I turn the key but the motor not swinging - the bendix moving, but the starter not turning ?

    So if all this is said and done then (if I understand correctly) - when I need to 'bypass' the solenoid somehow I would need to supply power to the low current 'input' connection (the thin wire 'blade' input) as well as the output terminal (the thick one going into the starter) by either shorting the two terminals, or supplying it power from the battery via jumperlead ?



    Quote Originally Posted by jfh View Post
    Check earth cable to engine, remove,clean and refit.

    Measure voltage on solenoid wire and on starter wire.
    Definitely something to do.


    Thanks for the replies !

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    Quote Originally Posted by Eisbein View Post
    Aaaaaaaaah

    Thank you for the diagram and explanation.

    Ok - so this makes sense to me then
    I was really under the impression that the solenoid only did the 'small to large current' switching and that the 'bendix movement' was done internal to the starter (btw - on my motorcycle it works that way)

    Is that then the 'click' I hear when I turn the key but the motor not swinging - the bendix moving, but the starter not turning ?

    So if all this is said and done then (if I understand correctly) - when I need to 'bypass' the solenoid somehow I would need to supply power to the low current 'input' connection (the thin wire 'blade' input) as well as the output terminal (the thick one going into the starter) by either shorting the two terminals, or supplying it power from the battery via jumperlead ?




    Definitely something to do.


    Thanks for the replies !
    The way to "jump" the starter if the Ignition key does not work is by "shorting the terminal with the small wire with the big terminal below it!
    Clicking of the solenoid is usually a sign that there is either not enough power to activate the solenoid , as jfh mentioned or the solenoid is packing up!



    Last edited by JWR; 2019/10/11 at 03:47 PM.

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    This was a problem that often occurred in the old rear-engined VW Kombis.
    The voltage drop from the ignition switch to the starter motor often prevented the bendix from kicking in (because of the length of wire).
    I solved it by installing a relay at the starter. The voltage was always enough to trigger the relay, and full 12V was available right there (battery to starter wire).
    "Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity" - Martin Luther king Jr

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    I would also then assume that people adding a normal relay to the low voltage input side of the solenoid (to give a more direct current from the battery) is in the case of the normal 'from the ignition switch' voltage drop that these cars are prone to having, causing the actuator in the solenoid to not move all the way as it should ?

    If I want to do/test that, then I add a normal wire from the battery through a 30amp fuse through the business end of a 30 amp relay and then use the current (no pun intended) 'input' connection from the ignition to activate the relay, making sure that the input voltage of the low current input is as close to 12v as it can be ?

    I suppose a normal 30amp automotive relay is more forgiving for having a lower input voltage than what a solenoid is.

    Sorry for stating the obvious and/or sounding a bit 'dof', but I am learning here


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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    I typed the above while this was added:

    Quote Originally Posted by 4eTouareg View Post
    This was a problem that often occurred in the old rear-engined VW Kombis.
    The voltage drop from the ignition switch to the starter motor often prevented the bendix from kicking in (because of the length of wire).
    I solved it by installing a relay at the starter. The voltage was always enough to trigger the relay, and full 12V was available right there (battery to starter wire).

    Confirmation then



    Quote Originally Posted by JWR View Post
    The way to "jump" the starter if the Ignition key does not work is by "shorting the terminal with the small wire with the big terminal below it!
    Clicking of the solenoid is usually a sign that there is either not enough power to activate the solenoid , as jfh mentioned or the solenoid is packing up!

    Thanks again for adding a picture and clarifying !

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    Btw - the starter was replaced (with the solenoid) about 2 years ago and it has done about 10 000km since (and it started doing the same thing before - hence why the starter was replaced by previous owner, so my money would be on the 'too low voltage' issue). This makes me think that the one common thing is the lower voltage being supplied from the ignition switch.


    Adding a relay to the low current input stage of the solenoid is a hellova lot easier and less complicated than farting around with thick cables, solenoid or some such.

    Thanks again.
    Last edited by Eisbein; 2019/10/11 at 04:08 PM.

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    As mentioned by 4eTuareg the wiring becomes old over time and the current drops to much! The relay will work but buy a good quality one ! Then connect battery power to terminal 30 , your wire to the starter to 87 , wire from Ignition to 86 and ground to 85. Make sure they supply a permanently open relay not closed. If you see a 87A terminal it is the wrong relay!

    Last edited by JWR; 2019/10/11 at 04:06 PM.

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    And while you are busy as mentioned by jfh make sure you have proper Earth on your engine block and close to the Starter also! I usually test by testing the battery power with a Multimeter and then by putting the negative probe at different places on engine block while keeping the positve probe on the + of the battery , looking if the voltage is the same as battery voltage also when cranking (shows if ground cable are corroded).
    Last edited by JWR; 2019/10/11 at 04:53 PM.

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    Thumbs up Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    Will do !

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    My D1 300 tdi has an earth cable from one of the three bolts holding the starter motor in to the chassis just underneath. I am sure it came from soryhill like that

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    Default Re: 1996 Discovery V8 starter/solenoid question (behavior and 'bypassing' the solonoi

    90% if electrical crap I've had with old Landies is the earth strap.

    I always replace that first if it looks in any way dodgy. I use welding cable with crimped ends that then get soldered as well.
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